This invention relates to a method and apparatus for mixing multi-component products and applying them to a surface using a pressure fed squeegee.
Thick, viscous coating materials are sprayed onto building walls and other items to provide a thick elastomeric coating. The sprayed material is often a plural component urethane/polyurea material. But typical spraying application equipment requires a large source of air and high air pressure. Typical applications require minimum of 7 to 11 CFM at 250-3000 psi. This typically requires the use of a very large and heavy 220 volt air compressor usually weighing hundreds of pounds. Further, the performance of the material is very sensitive to temperature, so either large, heated rooms are typically needed in order to maintain the temperature of the materials at an operating temperature, or else high temperature heat sources are needed with smaller, enclosed areas.
Thinner and much less viscous materials are applied by spraying, but the operators must be carefully trained or else the thinner paint drips and provides an unacceptable aesthetic appearance. The thinner materials are thus commonly applied using paint rollers, with pressurized paint rollers being able to continually feed one or even two different paints to the roller. Such rollers are described in U.S. Pat. Nos. 4,217,062 and 6,331,327, among others. Paint rollers allow a more uniform thickness to be applied than with roller application. Also, rollers do not create the mist or roller cloud that arises when such thin paints are sprayed, and thus there is less masking and fewer environmental issues with roller application rather than roller applications. Moreover, significantly less training is needed for roller application of paint and the uneven application of paint causing dripping is much less common than with sprayed coatings.
But rollers have not been used with multi-part coatings which activate upon mixing. Such use is not logical since the activated coating materials remain on the roller and the roller will thus quickly harden. Moreover, the activated material in the feed mechanism also hardens and will clog if the material remains in the feed mechanism for more than a few minutes. Further, application of multi-part coatings by spray guns or by a roller leave a coating that can vary greatly in thickness within a given and have a rough, splotchy appearance. If the surface being coated is chipped, spalled or contains other recesses, then coating with rollers or spraying will not fill in the recesses further resulting in an uneven surface finish. There is thus a need for a method and apparatus allowing an improved uniform application of such multi-part coatings.